Restoration of organic coastal and inland freshwater forests

Peatland forests occur worldwide in inundated soils where primary production and anaerobic conditions contribute to the building of soil organic matter (Günther et al., 2020). Greenhouse gas emissions (GHG) can be substantial from drained freshwater forests with organic soils. Therefore, rewetting peat via hydrologic restoration (see factsheet n°12 on Peatland restoration, this volume) can restore the function of these forests as carbon sinks and reduce their emission of certain components of GHG (Wilson et al., 2016). While the drainage of forests with organic soil is often a part of the process of agriculture, forestry, and peat harvesting, drying of peat can contribute to GHG emissions (Wilson et al., 2016; Günther et al., 2020). Reflooding of organic forest soils to restore hydrology can lead to an increase in tree health, production and organic matter accumulation (Middleton, 1999, 2020a), and a considerable overall reduction in CO2 and N2O emissions (Wilson et al., 2016). Depending on the duration and nature of the previous land-use, forested peatland restoration can be successful from seeds remaining in the seed bank or deposited via flood-pulsed dispersal (Middleton 1999, 2000, 2003). It is important to consider the nutrient status, hydrology and salinity of disturbed inland peat soils in peatland forest restoration (Chimner et al., 2017). Furthermore, the overall functional equivalence of restored wetlands to natural wetlands is a matter of debate (Kolka et al., 2018).